Police investigating Sweden's worst mass shooting were still trying to establish a motive as to why a lone gunman opened fire at an education campus in the southern city of Orebro, killing 10 people.

About 10 people, including the gunman, were killed on Tuesday at an adult education center in what Sweden’s prime minister called the country’s worst mass shooting. But a final death toll, a conclusive number of wounded and a motive hadn’t yet been determined hours later.

A mass shooting at an adult educational facility in Sweden on Tuesday was the deadliest such incident in the country's history, with 11 people killed, including the alleged shooter, law enforcement said on Wednesday.

Sweden's worst mass shooting left at least 11 people dead, including the gunman, and at least five seriously wounded at an adult education center west of Stockholm. The gunman's motive hadn't been determined by midday Wednesday as the Scandinavian nation — where gun violence at schools is very rare — reeled from an attack.

Sweden’s worst mass shooting has left at least 11 people dead, including the gunman, at an adult education center as officials warned that the death toll could rise.

A tragic mass shooting at an adult education center in Orebro, Sweden, resulted in the death of about ten individuals, including the gunman, marking the country's worst incident of its kind. As investigations continue,

Police in Sweden said "about 10" people were killed in a shooting at an adult education school . The shooting occurred at Campus Risbergska in Örebro, Sweden, the city said in a statement. Police say the shooter is believed to have been killed.

At least 10 people have died and many were wounded during a school shooting at an adult education center in southern Sweden on Tuesday afternoon.

Officials in Sweden have vowed to determine why a man killed 10 people, and apparently himself, in an unprecedented attack that's shaken their "society to its core."